According to a news item, there are suggestions in the U.K. to ban cousin marriages. Those who want this miss the whole point. The problem is amplified in case of marriage between two first cousins, both of whose parents as well as grandparents were also first cousins.

This is what has happened in the case of Pakistani Muslims, and this is the reason for the unusually large number of defective children being born to British Pakistani parents (as well as a significant population in rural Pakistan being mentally retarded). There is no danger of this happening in marriages between first cousins whose parents and grandparents were not first cousins.

true , its a medically proven fcat that inter-familial marriages give rise to diseases. Its not that they CREATE them but if somebody whose suffereing from the minor supressive symptoms marries someone whith the same they might have a child with Major symptoms , like in the case of thelessimia minor.